Investigation into stiffness degradation progress in glass/vinylester laminated beams under large deformations

There are many reports indicating that the maximum measured stress in the composite laminated beams under flexural loading appears different from that under tensile loading. The current study compares the results of Hashin failure criteria in the form of stress and strain components for prediction of failure strength in GFRP laminated beams. In the experimental program the composite laminates were tested under tensile and three-point-bending (3PB) loads. Then, it was trying to predict the flexural failure in laminates based on the measured ultimate stresses and strains in the tensile tests. The strain-based failure criteria employed in the FE models could achieve more admissible predictions for maximum load carrying capacity in the laminates compared to the stress-based criteria. Progressive failure analyses showed that due to higher elastic modulus of laminates under bending load, the maximum experienced stress under bending load becomes larger.